Merging three lists into into one dictionary

Question

I need to merge three lists into one dictionary. These lists are from reading a txt file I formatted, and here is a snippet from that file:

maker =['Horsey', 'Ford', 'Overland', 'Scripps-Booth']

year = ['1899', '1909', '1911', '1913']

model = ['Horseless', 'Model T', 'OctoAuto', 'Bi-Autogo']

Into the following:

car_dict = {'Horsey':1899,'Horseless','Ford':1909,'Model T','Overland' : 1911, 'OctoAuto', 'Scripps-Booth' : 1913, 'Bi-Autogo'}

Here is what I did:

def car_data_merge(car_maker,car_model,car_year):
    car_dict = {}
    car_merge = []

    car_dict = defaultdict(partial(defaultdict,list))

    for (car_maker,car_model,car_year) in zip(car_maker,car_model,car_year):
         car_dict[car_year][car_model].append(car_maker)
    print(car_dict)

When I enter this I get:

{'Horsey': defaultdict(<class 'list'>, {'1899': ['Horseless']})

Not all the data from list is shown and I don't want the defaultdict shown.

When I tried the following:

def car_data_merge(car_maker,car_data):
    car_dict = {}
    car_merge = []
    car_merge = zip(car_maker,car_data)  
    car_dict = dict(car_merge)
    print(car_dict)

    ###   car_data holds both year and model   ####

Only part of the data shows up:

'Horsey':'Horseless',':1909,'Model T

What should I do?

Answer 1

You were on the right track with zip, but beware that:

The returned list is truncated in length to the length of the shortest argument sequence.

If you're fine with that, you can zip your data into a list of tuples, zip the keys, and hand everything off to dict().

If you'd like to handle missing values, checkout itertools izip_longest (Python 2) or zip_longest (Python 3) where

If the iterables are of uneven length, missing values are filled-in with fillvalue.

try:
    # Python 2
    from itertools import izip_longest
    zip_longest = izip_longest
except ImportError:
    # Python 3
    from itertools import zip_longest

from pprint import pprint


def main():
    maker =['Horsey', 'Ford', 'Overland', 'Scripps-Booth', 'FutureX', 'FutureY']
    year = ['1899', '1909', '1911', '1913', '20xx']
    model = ['Horseless', 'Model T', 'OctoAuto', 'Bi-Autogo']

    car_data = dict(zip(maker, zip(year, model)))
    car_data_longest = {mk: (yr, md) for mk, yr, md in zip_longest(maker, year, model)}

    pprint(car_data)
    pprint(car_data_longest)

Output:

{'Ford': ('1909', 'Model T'),
 'Horsey': ('1899', 'Horseless'),
 'Overland': ('1911', 'OctoAuto'),
 'Scripps-Booth': ('1913', 'Bi-Autogo')}
{'Ford': ('1909', 'Model T'),
 'FutureX': ('20xx', None),
 'FutureY': (None, None),
 'Horsey': ('1899', 'Horseless'),
 'Overland': ('1911', 'OctoAuto'),
 'Scripps-Booth': ('1913', 'Bi-Autogo')}

Answer 2

How's this:

>>> maker =['Horsey', 'Ford', 'Overland', 'Scripps-Booth']
>>> year = ['1899', '1909', '1911', '1913']
>>> model = ['Horseless', 'Model T', 'OctoAuto', 'Bi-Autogo']
>>> d = dict(zip(maker,zip(year,model)))
{'Overland': ('1911', 'OctoAuto'), 'Horsey': ('1899', 'Horseless'), 'Scripps-Booth': ('1913', 'Bi-Autogo'), 'Ford': ('1909', 'Model T')}